Al-Si 合金中初晶 Si 的台阶生长

Step Growth of Primary Silicon in Al Si Alloy

采用离心倾液法研究过共晶Ａｌ－Ｓｉ合金初晶Ｓｉ的生长形貌时发现，初晶Ｓｉ存在生长台阶，台阶的高度为数十至数百微米，从初晶Ｓｉ根部至尖端，台阶的高度逐渐变小，初晶Ｓｉ存在位错台阶生长机制．这一生长机制能够形成棱柱体或棱锥体、八面体和球形初晶Ｓｉ，以及产生初晶Ｓｉ的分枝和形成初晶Ｓｉ的生长迹线．

Decantation during centrifugal casting was used to study the growth shape of primary silicon in hypereutectic Al Si alloy, and the results show that there are growth steps on primary silicon, the heights of the step are from tens to hundreds μm, the heights reduce from root to tip of primary silicon, and the growth mechanism by dislocation step is founded for primary silicon. According to the growth mechanism, primary silicon can become pyramidal or prismatic, octahedral or global one. Branching and growth trace of primary silicon are also come from the growth mechanisum.